// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_GPU_ACCELERATED_VIDEO_DECODER_H_
#define MEDIA_GPU_ACCELERATED_VIDEO_DECODER_H_

#include <stddef.h>
#include <stdint.h>

#include "base/macros.h"
#include "media/gpu/media_gpu_export.h"
#include "ui/gfx/geometry/size.h"

namespace media {

// An AcceleratedVideoDecoder is a video decoder that requires support from an
// external accelerator (typically a hardware accelerator) to partially offload
// the decode process after parsing stream headers, and performing reference
// frame and state management.
class MEDIA_GPU_EXPORT AcceleratedVideoDecoder {
public:
    AcceleratedVideoDecoder() { }
    virtual ~AcceleratedVideoDecoder() { }

    virtual void SetStream(const uint8_t* ptr, size_t size) = 0;

    // Have the decoder flush its state and trigger output of all previously
    // decoded surfaces. Return false on failure.
    virtual bool Flush() WARN_UNUSED_RESULT = 0;

    // Stop (pause) decoding, discarding all remaining inputs and outputs,
    // but do not flush decoder state, so that playback can be resumed later,
    // possibly from a different location.
    // To be called during decoding.
    virtual void Reset() = 0;

    enum DecodeResult {
        kDecodeError, // Error while decoding.
        // TODO(posciak): unsupported streams are currently treated as error
        // in decoding; in future it could perhaps be possible to fall back
        // to software decoding instead.
        // kStreamError,  // Error in stream.
        kAllocateNewSurfaces, // Need a new set of surfaces to be allocated.
        kRanOutOfStreamData, // Need more stream data to proceed.
        kRanOutOfSurfaces, // Waiting for the client to free up output surfaces.
        kNeedContextUpdate, // Waiting for the client to update decoding context
        // with data acquired from the accelerator.
    };

    // Try to decode more of the stream, returning decoded frames asynchronously.
    // Return when more stream is needed, when we run out of free surfaces, when
    // we need a new set of them, or when an error occurs.
    virtual DecodeResult Decode() WARN_UNUSED_RESULT = 0;

    // Return dimensions/required number of output surfaces that client should
    // be ready to provide for the decoder to function properly.
    // To be used after Decode() returns kAllocateNewSurfaces.
    virtual gfx::Size GetPicSize() const = 0;
    virtual size_t GetRequiredNumOfPictures() const = 0;

private:
    DISALLOW_COPY_AND_ASSIGN(AcceleratedVideoDecoder);
};

} //  namespace media

#endif // MEDIA_GPU_ACCELERATED_VIDEO_DECODER_H_
